Crack Sealing Configurations and Cost-Effectiveness Analysis

Cost-effectiveness is often the preferred method of determining which materials and procedures to use. We reviewed a cost effectiveness study on crack sealing materials for a U.S. State DOT. The study involved the construction of four experimental test sites within larger crack sealing projects. These sites include combinations of two sealant materials and six sealing techniques. The two materials were Right/Pointe and Maxwell. All hot poured crack materials met the ASTM D6690 standard.

The crack sealing technique included both non-routed and routed methods. Non-routed methods consisted of the Simple Band-Aid and Capped configurations. The Band-Aid configuration used a V-shaped or U-shaped squeegee to spread the sealant, and the capped configuration was accomplished by overfilling the crack slightly and allowing the excess sealant to settle. 

Routed methods included a “square” reservoir and a “shallow” reservoir. Square reservoirs were filled using three techniques: Flush, Recessed, or Band-Aid. This combination provided six crack sealing techniques; a) simple band aid (BA), b) capped (C), c) square reservoir and flush (SQ-F), d) square reservoir and recessed (SQ-R), e) square reservoir and band aid (SQ-BA) ,and f) shallow reservoir and flush (SH-F).

In the aforementioned study, monitoring of the test sites included visual inspections (for all of the sites), and nondestructive structural readings and surface distress identification. An estimate of the useful life of each crack sealing method has been determined from these investigations.

Two methods were employed to estimate crack sealing performance: Method A and Method B. The simplest method (Method A) used the forecasted life of a particular material/technique combination to estimate performance. For this method it is assumed that the crack sealant performance decays linearly over time. The minimum acceptable level of service of crack sealing (condition = 50 percent) is defined by the water’s ability to penetrate 50 percent of the sealed crack’s length. Field measurements conducted as part of this study were used to determine, and in some cases estimate, the time at which various crack sealant material/techniques combinations would reach this condition.

Method B was created because the exponential portion of the forecasting technique used to estimate useful life of crack sealing was sensitive to fluctuations in the distress data. As such, this method used measured performance conditions collected from test sites at specific time intervals. As in Method A, Method B defines the minimum acceptable level of service of crack sealing to be when its condition = 50 percent, i.e., when water is able to penetrate 50 percent of the sealed crack’s length. This method provides a more accurate estimate of the effectiveness of crack sealing material/technique combinations since it considers real performance values over time rather than an estimated performance derived from estimates of useful life. The effectiveness of the material/technique combinations was determined using both methodologies. The effectiveness was divided by the average installation cost to determine cost-effectiveness as illustrated in the table below.